Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds real behavioral context beyond that: pricing is in KRW per month, the plan must cover every title, and the response includes per-title service assignment plus up to two alternatives. It does not mention the 15-title cap or what happens when no plan covers all titles, which keeps it below 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

One dense sentence front-loads the primary output (cheapest subscription set) before the secondary details (per-title service, alternatives). Nothing is wasted, though the trailing 'Pass StreamPick ids or titles' duplicates schema content rather than earning its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description carries the burden of describing returns and does so — currency, coverage guarantee, per-title mapping, and alternatives. Combined with readOnly annotations, an agent has what it needs to call this correctly. Missing only failure/coverage-gap behavior for a single-parameter tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

There is a single parameter with 100% schema description coverage, so the schema already documents both accepted id format ('tmdb-tv-93405') and Korean/English titles. The description's 'Pass StreamPick ids or titles' restates the schema without adding format or edge-case meaning. Baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a specific computation and resource: the cheapest set of Korean OTT subscriptions/bundles covering a title list, plus per-title service assignment and alternatives. An agent can tell this is an optimization tool rather than a lookup. It does not explicitly contrast itself with siblings such as where_to_watch, so it stops short of a 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied by the phrase 'covers every title in a list' — the agent must infer that this tool is for multi-title cost optimization rather than single-title lookup. There is no explicit when-to-use, when-not-to-use, or named alternative among the siblings. It is adequate but leaves routing decisions to inference.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.